This disclosure relates to test and measurement instruments, in particular to test and measurement instruments and methods of switching waveform display styles of the same.
Test and measurement instruments can be used to display waveforms associated with information gathered from one or more electrical signals. For example, a conventional oscilloscope can acquire electrical signals through a particular channel, sample the electrical signals, and display the sampled information as a waveform or overlapped waveforms. In one scenario, the oscilloscope can sample peak detect data, or in other words, minimum and maximum values within successive periods of time and store these values in memory. In another scenario, the oscilloscope can apply lowpass filtering to the electrical signals and display the lowpass sampled data in parallel with the peak detect data. Commonly-owned US Patent Application Publication 2007/0217694 to Sullivan et al. (hereinafter “Sullivan”), filed Mar. 20, 2006, entitled, WAVEFORM COMPRESSION AND DISPLAY, which is herein incorporated by reference in its entirety, discloses such a system.
Sullivan teaches that two waveforms can be overlaid. For example, a foreground waveform (i.e., filtered waveform) can be overlaid with a background waveform (i.e., glitch capture waveform) so that both waveforms can be simultaneously observed. Traditionally, filtering has involved a tradeoff. The waveform the user is looking at becomes cleaner and easier to measure, but the user loses the ability to see noise and high-frequency glitches. Sullivan avoids that trade-off by letting the user see a filtered waveform along with the noise and glitches that were filtered out. But Sullivan does not disclose how best to display these signals, or how to control their display, including how to turn one or the other of them off.